RedRed

RedRed is a library that uses Redis to provide invisible, atomic persistence for Ruby objects. It's at best a proof of concept; I have no intention that anyone ever use it for anything, especially in production. But it's kind of a cool idea.

Usage

require 'red_red'

class Post < RedRed::Object
  rattr_accessor :title
  rattr_accessor :blog
end

class Blog < RedRed::Object
  rattr_accessor :name
end

post = Post.new
post.title = 'My Cat Did The Funniest Thing!'
post.blog = Blog.new
post.blog.name = 'All about my cat'

post.redis_id #=> "f561b40e-65d6-11df-9014-0024e897e5d6"

# then sometime later

post = Post["f561b40e-65d6-11df-9014-0024e897e5d6"]
post.title #=> "My Cat Did The Funniest Thing!"
post.blog.name #=> "All about my cat"

How it works

The first time you set an attribute on a RedRed::Object, a UUID is generated for the object, and stored in memory. That UUID is used as a prefix for keys that contain attributes of that object.

When you set an attribute, it's immediately written to Redis with a key that contains the object's UUID and the name of the attribute. If the attribute value is itself a RedRed::Object, then the key will reference that object's own UUID. Otherwise, it's just marshalled.

To Do

• Use constant-like semantics for object access by natural key
• Support atomic operations on Redis scalar types (strings, numerics)
• Support arrays (Redis lists), sets, sorted sets
• Support hashes (not available natively in current Redis release)
• Garbage collection???

Caveats (or Why No One Should Use This)

• Persisted objects live forever. There is no concept of deletion.
  • This could maybe be handled with constant-like retrieval and GC
• For performance, attributes are still stored in memory after first retrieval / setting. So, object state can be inconsistent with persisted state.
• It makes lots and lots of queries to Redis. Redis is fast, but network latency would probably preclude using this with a non-local Redis instance.

This is free software.